//
// Created by wze-zero on 2024/9/17 017.
//
#include <iostream>

using namespace std;

int main() {
    int n, m, num, sum = 0;
    cin >> n >> m;
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < m; ++j) {
            cin >> num;
            if (num > 0) {
                sum += num;
            }
        }
    }
    cout << sum << endl;
    return 0;
}